MFC r355940:

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
9.0.0 final release r372316.

Release notes for llvm, clang, lld and libc++ 9.0.0 are available here:

https://releases.llvm.org/9.0.0/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/clang/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/lld/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/projects/libcxx/docs/ReleaseNotes.html

PR: 240629
MFC after: 1 month

Upgrade our copy of clang, llvm and lldb to 3.5.0 release.

Please note that this version now requires C++11 support to build; see
UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.5.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.5.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Roman Divacky, Andrew Turner, Justin Hibbits and
Antoine Brodin for their invaluable help with this import.

Approved by: portmgr (antoine)
MFC after: 1 month

Merge the projects/clang-sparc64 branch back to head. This brings in
several updates from the llvm and clang trunks to make the sparc64
backend fully functional.

Apart from one patch to sys/sparc64/include/pcpu.h which is still under
discussion, this makes it possible to let clang fully build world and
kernel for sparc64.

Any assistance with testing this on actual sparc64 hardware is greatly
appreciated, as there will unavoidably be bugs left.

Many thanks go to Roman Divacky for his upstream work on getting the
sparc64 backend into shape.

MFC after: 1 month

Import a whole bunch of llvm trunk commits to enable self-hosting clang
3.4 on Sparc64 (commit descriptions left out for brevity):

r196755 r198028 r198029 r198030 r198145 r198149 r198157 r198565 r199186
r199187 r198280 r198281 r198286 r198480 r198484 r198533 r198567 r198580
r198591 r198592 r198658 r198681 r198738 r198739 r198740 r198893 r198909
r198910 r199014 r199024 r199028 r199031 r199033 r199061 r199775 r199781
r199786 r199940 r199974 r199975 r199977 r200103 r200104 r200112 r200130
r200131 r200141 r200282 r200368 r200373 r200376 r200509 r200617 r200960
r200961 r200962 r200963 r200965

Submitted by: rdivacky